15mm pipes feeding multiple rads

S

snadge

Hi

I have noticed that our central heating (combi boiler) rad pipes are 15mm that feed off each other ... is this OK/Safe..?

what I mean is the Boiler has the 22mm pipes coming off the boiler but then 15mm pipes along to the rads and each rad is fed from another rads 15mm pipe, returns are the same... my dad tells me that the plumber told him that your supposed to have 22mm pipes under the floor upstairs and down (we dont) and each rad has its own 15mm pipe coming off the 22mm one and fed back to the return 22m pipe on its own 15mm one - but ours is just a maze of 15mm pipes.

is this a problem?

whoever done the pipework WAS a cowboy, Im not a plumber but Ive seen some major flip-ups under the floor with the pipework.


thanks in advance
 
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All main flow and return pipes from the boiler should be run in 22mm. It is better to run 22mm as far as possible before reducing to 15mm. Are you having any problems?
 
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It all depends!

Traditionally 15 mm has fed up to 3-4 kw. That means in a small house 22 mm splitting to 15 upstairs and same downstairs is fine.

With a condensing boiler you can virtually double the power handling capacity.

Tony
 
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Traditionally, about 4kW was the limit, in total, for 15mm pipes. That's two substantial radiators. The limit is where the water flow noise gets to be noticeable, so it's not hard and fast.
Modern condensing boilers run with lower flow rates, soyou actually have more leeway.

More of a problem with afew long and heavily loaded pipe runs, is balancing the system (look it up ;) ). If you have a low resistance part in parallel with a high resistance part, it's difficult to get the right flow through both of them.
 
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S

snadge

thanks for the quick replies guys...
really appreciate it! :)

we arent having any NOTICEABLE problems with the flow, the rads heat up just fine - our boiler is an Ideal ISAR HE30 (which I know are poop) and we have 4 rads up and 4 rads down

we DO have a problem with a leaky union valve just under the boiler itself, the tap on the valve that lets out testing water is broke and leaks 1 drip every 30 seconds or so which we are waiting to get fixed, when it drips air must be getting into it and going up to the vertical rad upstairs as after 4-5 days only half the rad heats up because the air goes to top and blocks the flow through the pipes and I have to bleed it, once every week or so im topping up the pressure.

but apart from that issue everything works fine.

I ask because if it needs sorting then we need it done before we continue with doing up the house

thanks again
 
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when it drips air must be getting into it and going up to the vertical rad upstairs as after 4-5 days only half the rad heats up because the air goes to top and blocks the flow through the pipes and I have to bleed it, once every week or so im topping up the pressure.

Who told you that?.
 

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